1. Field of the Invention
The present invention relates to an extraction tool that can be used for removing packing from the stuffing box of a valve. The extraction tool of the present invention is particularly useful for removing packing from around a circular cross-sectional valve shaft mounted in the stuffing box of a manually operated fluid control valve. The extraction tool is comprised of a main, generally cylindrical working member having a sidewall with a plurality of cutting teeth at the perimeter of one of the open ends of the working member. A handle extends laterally from the other open end of the working member. An arcuate opening is provided in the sidewall and extends between the open ends of the working member. The arcuate opening is preferably only slightly wider than the diameter of the valve shaft. This provides for positioning the extraction tool on the valve shaft without having to remove the valve handle wheel from the valve shaft. The extraction tool is then rotated about the valve shaft so that the cutting teeth bite into the packing to pulverize the packing surrounding the valve shaft. The arcuate opening also acts as a conduit for removing the pulverized packing from the stuffing box. Thus, the extraction tool is a reliable and an easy to use tool that is particularly useful for removing old and worn packing from the stuffing box of a valve so that the packing can be replaced before fluids controlled by the valve leak past the packing.
The extraction tool is also useful for removing packing from around a shaft means mounted in a housing where the shaft means reciprocates inside the housing. An example of this would be a reciprocating pump shaft or a reciprocating lance tube and stuffing box that are concentrically mounted around a feed tube as in a furnace. In those embodiments where the shaft means is actuated in a reciprocating motion, the shaft means need not necessarily have a circular cross-section, but instead can also have a polygonal cross-section perpendicular to the longitudinal axis of the shaft means.
2. Description of the Prior Art
The prior art has described various types of tools that are useful for removing packing material from around shafts, such as those found in fluid control valves. Most of these packing extractor tools have cutting elements that are formed as augers, picks or corkscrews. In the removal process, the cutting element is forced to bore into the packing material. The extractor tool is then manipulated to disintegrate and clean the packing material from between the valve stem and the stuffing box holding the packing material.
The problem with a great many of the prior art packing extraction tools is that they require that the valve handle wheel be removed from the valve stem so that the extractor tool can be mounted on the valve stem. Removing the valve handle wheel can be time consuming and difficult if the valve is located in an area of limited accessibility. Illustrative of this type of packing extractor tool are U.S. Pat. Nos. 1,195,220 to Hendren; 2,822,713 to Schmidt; 3,014,271 to Englund and 4,226,016 to Carr.
U.S. Pat. No. 3,149,514 to Shaub describes a packing extractor having a yoke that breaks down into two halves to enable the yoke to be assembled around a valve stem. The yoke is then threaded onto bolts that are normally used to hold a compression nut against the packing. A number of corkscrews are provided on the yoke. The corkscrews are rotated to worm into the packing. The yoke is then backed away from the stuffing box. This causes the corkscrews to pull the packing out of the stuffing box. The problem with this device is that if the packing is brittle and worn, the corkscrews may not be able to cleanly remove all of the packing from the stuffing box. In that case, the remaining packing will need to be cleaned from the stuffing box by a separate tool.
Other types of packing extractors have also been described that do not require the valve handle wheel to be removed from the valve stem. However, these extractors are more complicated than the extractor tool of the present invention or they require that the valve be in a relatively accessible area.
U.S. Pat. No. 3,443,460 to Johnston, Jr. describes a packing extractor tool that is comprised of an open helix having a handle. The helix is able to be mounted on a valve stem without removing the valve handle wheel. The helix can then be manipulated to peel the packing out of the stuffing box. This requires that the tool be rotated around the valve stem through several rotations, which means that the valve must be in a relatively accessible area. As the extractor tool is being rotated about the valve stem, a cutting edge of the helix digs into the packing. The cutting edge, however, has a tendency to bury in the packing and to thus become lodged. The extractor tool must then be worked back and forth to dislodge the helix from the packing.
U.S. Pat. No. 3,651,717 to Johnston, Jr. describes a packing extractor tool that is formed as an open helix. One end of the helix is attached to a breakdown coupling that can be mounted on a valve stem without the need to remove the valve handle wheel from the valve stem. A spanner wrench is used with the coupling to bore the helix into packing material. This device has many parts and is complicated to assemble. Also, a cutting edge of the helix tends to become lodged or buried in the packing as the helix digs into the packing in the stuffing box. This requires that the helix be worked back and forth to dislodge the extractor tool from the packing.
U.S. Pat. No. 4,509,392 to Smith describes a packing extractor that is formed in the shape of a pair of opposed levers joined by a fulcrum. The levers form a handle that when compressed separates the opposite ends of the levers to force a cutting projector, mounted on one of the levers, into the valve packing. The extractor must be braced against a valve hand wheel or some similar stop mechanism and requires numerous thrusts into the packing to dislodge the packing. Also, the downward thrust of the cutting projection may actually tend to compress some of the packing tighter into the stuffing box.
U.S. Pat. No. 4,611,510 to Morton describes a packing removal tool that is particularly adapted for use with feed tubes for a soot blower. The packing removal tool is mounted on a feed tube, and as a lance tube and its stuffing box are retracted from the furnace, a cutting edge of the tool digs into the packing in the stuffing box. This packing removal tool is not particularly suitable for use with a manually operated valve.
What is not shown by the prior art and what is needed is a packing extractor tool that can be mounted on the valve shaft of a manually operated valve without having to disassemble the valve handle wheel. The packing extractor tool must also be provided with cutting teeth that scrape at the packing without becoming lodged in the packing as the packing is removed from the stuffing box. This prevents damaging the valve shaft and the stuffing box as the extractor tool is being manipulated and rotated around the valve shaft to disintegrate and pulverize the packing.